Felicia Boots, 34, is accused of murdering her 10-week-old son Mason, and his 14-month-old sister Lily at their upmarket family home.

Boots, wearing grey tracksuit bottoms and a dark grey jumper, spoke in a soft Canadian accent when she confirmed her name and address at Lavender Hill Magistrates’ Court in Battersea, south west London.

She was remanded to appear at the Old Bailey on Tuesday.

As she left the court she waved to her parents and a friend who were watching proceedings from the public gallery.

The children were found unconscious by their father, Jeff Boots, when he returned home from work on Wednesday. Emergency services were unable to revive the children.

Mrs Boots, a trained hairdresser, was arrested at the semi-detached home in Killarney Road, Wandsworth, south west London.

A formal cause of death has not yet been determined, police said.

Both Mr Boots, an investment banker, and his wife are understood to have moved to the UK in the last few years from Canada.

Up at The O2 has teamed up with London24 to give one lucky reader the chance to experience urban mountaineering this summer with an exhilarating 90-minute climb across the roof of one of London’s most iconic landmarks.